Farming Syrup Trees: Maple Sugaring and More

Maple sugaring is the ancient practice of tapping sugar maples for their sap before boiling it down into syrup, and it’s an excellent way to extend the forest farming season.

By Ken Mudge and Steve Gabriel

| September 2015

Liz Falk of Wellspring Forest Farm adds fresh sap to the boiling pan. Sap is 98 percent water, with a slight taste of sweetness. One will never have cleaner water than the water filtered through a tree!Photo courtesy Chelsea Green Publishers

A medium-scale boiler setup at Wellspring Forest Farm, designed to handle the sap from about a hundred trees. The pan was bought used from a maple producer, the firebox is made of cinder blocks, and the chimney stack was reclaimed from neighbors when they replaced their chimney.Photo courtesy Chelsea Green Publishers

A spun aluminum bucket and lid, the traditional Canadian-style bucket. Used metal buckets can be purchased for a reasonable price but are increasingly hard to find.Photo courtesy Chelsea Green Publishing

Tapping trees at Wellspring Forest Farm. Modern cordless drills hold a decent charge and can tap dozens of trees before needing a recharge. Be sure to drill straight into the tree to avoid inflicting more damage than is necessary.Photo courtesy Chelsea Green Publishing

"Farming the Woods," by Ken Mudge and Steve Gabriel, is an exploration of forest farming as a sustainable practice, from maple sugaring to growing medicinal herbs and mushrooms to harvesting fruits and nuts.Cover courtesy Chelsea Green Publishing

Ken Mudge and Steve Gabriel demonstrate that forestry and farming are not mutually exclusive in Farming the Woods (Chelsea Green Publishing, 2014). Learn how to cultivate, harvest and market high-value nontimber forest crops, from medicinal herbs and ornamentals to fruits, nuts and syrups. The following excerpt is from chapter 4, “Food from the Forest: Fruits, Nuts, and More.”

One of the oldest forms of forest farming comes in the tapping of tree sap for delicious and nutritious products that arrive as the seasons change (thaw) from winter to spring. By far the most common practice is with sugar maple, though there are several other trees that warrant attention, depending on the location of a forest farming operation.

Maple

Maple sugaring is the first act of spring for farming in the Northeast. It signals the awakening of the plant kingdom, with copious amounts of sap flowing up from the roots of the sugar maple (Acer saccharum), awakening dormant buds and pushing forth flowers and eventually leaves that will be the solar array for the trees and the forest. Even though humans have harvested sap since pre-Colombian time, mainly in North America, the entire physiology of the sap run is not fully understood.

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The process of collecting and boiling sap has barely changed over time. Innovations have mainly come in how sap is moved from the tree to the fire and how quickly the boil is conducted. But the main process is both simple and timeless. Native Americans used sharpened stones and later hatchets, hacking a V into the trunk of the tree and collecting sap in a wooden trough. Sap was boiled by cooking rocks in a hot fire, then placing them into the sap and constantly replacing rocks throughout the night. The natives also relied more heavily on letting sap freeze, which naturally separates water from sugar. The remaining liquid was then boiled off, but it took a lot less time than boiling alone. Some sugarmakers still take advantage of this freeze/boil strategy today.

When European settlers arrived, so did metal. Buckets were easier to make, maintain, and store. Since metal can come into contact with fire, the boiling process was revolutionized. Large cast iron kettles over fires worked but also wasted a lot of heat. Eventually metal tanks were fabricated to fit perfectly over fireboxes, which channeled fire toward the pan, thus making for a more efficient boil.

Modern life brought plastic, making sugaring cheaper to set up and maintain. Tubing lines can be cleaned out and reused for several seasons. They are particularly helpful on steep sites and those challenging to access. Tubing systems are now the maple industry’s standard, mainly because agricultural practices have all tended to evolve to replace human labor with technology, which often equals efficiency. The addition of vacuum systems has also led the yield per tree to increase. Fuel to boil sap is equally diverse, with many sugarmakers abandoning wood firing, choosing to boil sap with gas or oil as the fuel. Today the choice of equipment is a combination of the sugarmaker’s desired scale and personal goals for the farm.

Maple Sugaring Basics

Following are some of the key points to keep in mind with regard to sugaring. Some vocabulary is useful, too; a “sugarmaker” is one who collects and boils sap into maple products. A “sugar bush” is the collection of trees that are tapped for sap, while a “sugar shack” is the place sap is brought to boil. And finally, a “run” is the period of time when trees are producing sap for collection.

Sap Is 2 Percent Sugar

What comes out of the tree is overwhelmingly water, and likely the cleanest water one will ever drink. Sap is an amazing tonic and will keep in the fridge for up to a week (a similar shelf life to milk). The 2 percent sugar content is an average, with some trees occasionally giving more. Sugarmakers often assume that 40 gallons of sap make a gallon of syrup. If the weather is cold enough to freeze the collected sap, it is worth removing any frozen chunks, which are almost entirely water. It will significantly reduce boil time.

One Tap per 10-Inch-Plus Diameter Tree

While opinions vary, it is best to tap trees that are 10 inches in diameter or greater. Because of the increased environmental stress from climate change and other factors, most Extension agents recommend only one tap per tree, regardless of how big it is, though some choose to add a second tap to trees 18 inches or greater. This is a choice based on short-term yields versus long-term health. When in doubt, tap less.

A Quart per Tree

In any average season one can expect each healthy mature tree to produce enough sap (about 10 gallons total) to boil down to a quart of syrup. This is a rough figure, although seasonal variables make this a very flexible number. So ten trees would yield 2.5 gallons, fifty trees about 12.5 gallons, and one hundred trees about 25 gallons.

Runs Highly Variable

A “run” is a period of time when the temperatures are warm enough for the sap to flow, then cool down, stopping the flow. No two seasons and no two runs are alike. The basics are that sap runs when temperatures rise above freezing (32 degrees F) and stop when they drop below freezing. Yet things quickly get more complicated. Sap flow is much like a faucet. It can run slowly or rather quickly, depending on conditions. A day with temperatures that barely get over 32 degrees F is a slow run, but it seems that over 45 degrees F the run also slows.

The ideal run starts with overnight temperatures dropping down into the mid-20s. Then a quick warmup in the morning follows, with temperatures reaching around 40 degrees before a long descent back into freezing temperatures. Of course, the backyard sugar farmer cannot control the weather, so sugaring requires patience and flexibility. It also forces sugarmakers to pay attention to the subtleties of the natural world.

Syrup Is 67 Percent Sugar

Sap is most often boiled down to a syrup that is 67.7 percent sugar. This ratio is shelf stable, requiring no refrigeration if bottled properly. Any less sugar and the product will mold at some point, whether in weeks or months. At a higher sugar content, the syrup begins to crystallize.

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Scale: Where to Begin?

It’s easy to tap trees: The key is to consider ahead of time how many are appropriate. One approach is to consider a goal of how many gallons of syrup to produce. Since a tree provides on average a quart of syrup per season, a starting point would be that tapping four trees would provide about a gallon of finished syrup. Those who heat their home with wood can easily keep up with this—adding a bit of sap with each run to a pot on the woodstove, then finishing a gallon at the end of the season over the main stove, keeping in mind that when syrup gets close to finished it can easily burn.

Once you get over five trees it begins to get more complicated. Boiling will need to happen outside, as the amount of steam coming off a boil could do damage to a home. Besides prefabricated rigs that you can order from supply companies, the easiest (and cheapest) backyard rig starts with cinder blocks; it’s easy to create any dimension you want. Backyard sugarmakers usually tap somewhere between ten and two hundred trees.

As for boiling pans, a restaurant supply company can provide a 6- or 8-inch-deep “hotel pan” in a variety of sizes, which can work quite well on cement blocks. Multiple pans allow for you to begin tapping ten to forty trees with ease. Beyond that a local welder can be contracted to fabricate a pan, or a used pan can be purchased from a sugaring supplier.

Commercial sugarbushes usually start at a thousand taps or even as big as sixty thousand, though a few folks that sell syrup still maintain smaller operations. The experience of sugaring at this scale is both intense and highly rewarding, with long days and late nights around the boiler becoming the norm for several months. Successful operations usually combine syrup with other strategies. Some host pancake breakfasts on weekends during sugaring season, combined with tours of facilities and the woods. Others engage in “community sugaring,” working with school groups and families interested in the process. Festivals, statewide open houses, and mail order to places around the globe that don’t have access to maple syrup are also good strategies.

Buckets vs. Tubing

Once the number of trees for tapping is determined, the next step is to decide on the method you will utilize to collect sap. This decision includes thinking of what materials are preferred (metal vs. plastic), the aesthetic desired in the sugarbush, and how you want to use your limited labor.

Buckets

This choice involves setting up buckets to collect the sap, which will need to be emptied and the sap moved to the sugarhouse. This can be labor intensive, though on a gently sloped piece of forest with good access, a single person can easily harvest hundreds of buckets in under an hour.

Traditional buckets are made from either galvanized tin or spun aluminum. The bucket contains a hole that hangs on the tap, which is pounded into the tree. Taps, also know as spouts or spiels, come in two sizes; 5/16 inch and 7/16 inch. It is widely recommended that the smaller 5/16 be used; these are sometimes called “health spouts,” since you are wounding the tree in tapping it, and though the smaller size won’t affect the amount of sap collected, it will allow the tree to heal faster. There are many types of spouts made of metal and plastic. Old and rusty spouts should not be used.

A lid is also part of the setup, to keep debris and rain from falling into the bucket. Because the maple industry has largely adopted tubing systems, there is currently very limited production of new buckets. A set of bucket, spout, and lid could easily cost $20 to $30. Luckily, since so many commercial sugarmakers have abandoned buckets, used ones are available, selling for $8 to $15 a set, though it does take a bit of hunting around to find them for sale. Over the last few years, these have become harder and harder to come by.

A bucket system can be easily constructed from locally available materials, utilizing food-grade 5-gallon buckets. These buckets are either hung on the tree or placed on the ground beneath the tree, and a plastic tap and short piece of line connect the tree to the bucket through a hole drilled in the bucket lid. A 5-gallon capacity means sap won’t need to be collected every day—a nice side benefit. Sometimes if two or three trees are really close together they can even share the same bucket. There are many variations on bucket systems that deviate from these basic examples; the key is to keep the sap clean and isolated from outside elements.

Tubing

Where access, steep slopes, or limited time prevails, tubing systems are the natural choice. Tubing is available from sugaring supply companies at a low cost, around $.10 per foot. Tubing can be used to drop into buckets or tanks as mentioned, but it is best utilized by collecting trees from the top to the bottom of the slope along one length.

“Drop lines” consist of a spout and short length of tubing that connect to the main line, which runs downhill. Most tubing lines are 5/16 inch, though when multiple lines come together a “mainline” can be added, usually 1/2 inch or 3/4 inch, to accommodate the increased volume. A tank at the bottom of the line allows for a single collection point and ideally is right at the point where sap will be boiled. If a sugarmaker decides to go with tubing, it is highly recommended she read up on the topic and work with a local experienced person to learn the technique. Most modern tubing systems employ a vacuum system, which pulls sap from the trees and can boost yields while likely not damaging the tree.

Tapping the Trees

This part of sugaring is the most important to take extra care and detail with, as tapping is essentially wounding the tree, and the goal is to create a clean wound that will heal quickly after the tap is removed. It is worth purchasing a special tapping drill bit from a maple supplier, as it will last forever and it is specially engineered to leave a cleaner hole, critical to helping the wound heal itself. Tapping can be done anytime from early to late February (at least in Upstate New York) through the end of the season in late March to even mid-April some years. The key is to avoid leaving taps in longer than six to eight weeks; otherwise the tree will naturally heal itself around the tap hole and the tap will be almost impossible to remove. Taps should be removed as soon as trees break bud, if not sooner.

To select a spot for tapping, first examine the entire tree. Is the crown complete, and does it appear healthy? Avoid tapping areas that appear diseased or damaged. If the tree has been tapped in previous years, tap the opposite side from the most recent hole. No trees smaller than 10 inches should be tapped.

Drill with a high-speed cordless drill about 1.5 inches into the tree. Take extra care to keep the drill straight in and out of the tree, to avoid an “oval” hole. The goal is to get through the sapwood and slightly into the hardwood center of the tree. Insert the tap and hammer lightly until the tap is snug in the hole. Hammering too hard will result in split wood, which takes longer to heal.

Collection and Storage

When below freezing nighttime temperatures are followed by days of rapid warming above freezing (ideally around 40 degrees F), a sap run will occur. Checking buckets or storage tanks becomes an exciting daily chore and teaches the sugarmaker a lot about the subtle dynamics of the awakening spring. No two runs, and no two seasons, are ever alike. There will be days when the operation is overwhelmed with sap and days when you are surprised by how little comes out of the trees.

After a run, sap should be collected and boiled as soon as possible. If temperatures drop below freezing at night, sap will be effectively refrigerated and will last many days until the sugarmaker is ready to boil. Sustained temperatures between 45 and 60 degrees F can cause sap to spoil in as little as twenty-four to forty-eight hours. Spoiled sap will appear cloudy and taste bad. It is easy to keep a storage tank cool by piling snow around it, keeping a lid on it, and sheltering it from sunlight.

Boiling

The major time and energy sink of sugaring is in the boil, and efficiency can be maximized through several strategies. One key way is to outfit any backyard-sugaring rig with a stovepipe; a 6- to 8-foot rise will provide natural draft and keep the fire burning hot. Some folks install a small fan to blow air through the fire as well. Try to construct the evaporating rig to be as airtight as possible to direct the flow of air.

The reality is that sugaring takes time. Expect to get a fire rolling and be keeping watch over it for many hours. This provides a great excuse to have a party and share the fun of standing in the woods boiling with friends and neighbors who come around to warm by the fire, share stories (and a sap toddy), and welcome spring. Inoculating mushroom logs is a great task to engage in while doing a boil. There is also something to be said for sitting quietly in the forest, listening to the sounds around as the fire hums along. It’s a truly wonderful time.

Finishing

No matter what size setup you use, it will be nearly impossible to bring sap to that magic 67.7 percent number on a fire-driven setup. Most sugarmakers boil as much as possible over the fire, then finish on a propane or electric stove, where the sap can be closely monitored and the heat source easily adjusted.

Syrup is finished when the boiling temperature reaches 219 degrees F (the boiling point of syrup), which can be determined with a candy thermometer. For a more accurate reading, use a syrup hydrometer, which will measure the sugar content of your liquid. It is critical to get the syrup as close to the correct ratio of sugar (67.7 percent); if it’s too low it will become moldy and if too high it will crystallize. Moldy syrup can always be revived by bringing it to a boil and skimming off the mold, so it’s not that big a deal in the end. Remain vigilant when boiling on fire and stove; when the level becomes too low or toward the end of finishing it is easy to scorch or burn the syrup—which is a sad fact, indeed—to have the product ruined after many hours of work!

Bottling

The best method for preserving backyard syrup is canning it in mason jars. Sterilize the jars and lids in boiling water, then pour the freshly boiled sap into the jars once the sap is between 180 and 219 degrees F, which will be warm enough to seal the jars (no hot bath needed). Jars should be warm when you pour the sap in them, as the hot sap can break the jars if they are cold. Of course, a wide range of other containers can be used to store syrup, which if cooked to the correct percentage should be shelf stable. If you don’t want “sugar sand” (the unfiltered sediment, which is harmless) to settle in the jars, use a cloth filter before bottling. Syrups should be stored in a cool, dark place away from direct light.

Walnut Syrup

Walnut (Juglans spp.) trees are wonderful nut producers and also provide potential high-value wood products. If trees are not candidates for the latter, then tapping in addition to nut harvest can be a nice combination of yields for the forest farmer. The tapping of walnut also opens up the possibility of sugaring for forest farmers in warmer temperate climates found in the southern United States and parts of the Midwest.

While the basics of tapping, harvesting, and boiling walnut are the same as with maple and birch, the potential yields are much lower. Walnut trees have a similar sap-to-syrup ratio as maple syrup, but sap yields (volume per tree) from trees appear to be lower. Walnut sap flows in response to the freeze/thaw dynamics similar to those that make the maple sap run, so often the need to boil is concurrent with maple syrup. While there is still research to be done, it isn’t highly likely that black walnut syrup will develop into its own market. Instead, it is recommended as a hobby pursuit or for the commercial grower to consider boiling walnut along with maple, and selling this combination for a higher price. Indeed, a small number of growers are doing this and getting as much as $60 a gallon for their walnut-maple syrup (compared for $45 a gallon for pure maple). This is mostly because of the novelty.

On its own, walnut syrup is similar to maple syrup; it can be quite astringent but is infused with the nutty taste one might expect from it. Researchers from Kansas State University recently experimented with producing black walnut syrup, then did some consumer research on preferences for black walnut versus maple syrup. They found no significant differences on the likability scale between these two syrups and concluded that black walnut syrup could develop as a niche market in the Midwest.

Usually it isn’t recommended that trees destined for timber markets be tapped, whatever the species. Yet an interesting recent anecdote is that tapped maple wood has been successful when sold as a high-value wood in niche markets, where the staining is seen as a unique feature desirable to some for decorating homes and celebrating the rich tradition of sugaring. The same potential could hold true for black walnut, though it’s hard to know. One major difference is that the discoloration left by a tap in maple wood is often a dark stain on white wood, but the black walnut develops a very dark brown heartwood, and it’s unclear what effect tapping would have on this. So if timber is a clear goal for walnut trees, it’s better to leave them untapped. Walnut trees with poor form and defects are good possible candidates for experimentation. Trees with a decent timber potential could also be tapped lower on the tree.

Birch Syrup

Those who already tap maples may want to consider also tapping birch trees, should they be fortunate enough to have a stand in their woods. Birch sap doesn’t usually begin flowing until the end of maple season, and since the same equipment is used for both, maple producers could simply switch over and continue to make syrup. Of course, there is a catch: While a gallon of finished maple syrup takes 40 to 50 gallons of sap, it’s more like 100 to 200 for birch, because it has a much lower sugar content (1 to 1.5 percent).

The extra time and expense can pay off, however, as birch syrup is sold for $350 to $400 a gallon (maple is $45 to $60 for a gallon), and with demand far outstripping supply, it’s a farmer’s market. Most of the available birch syrup comes from Canada and Alaska, where birch forests are more common. But many northern states have the potential to “tap” into their birches as a source of syrup.

Birch syrup is not for pancakes. It’s fruity, spicy, and sometimes reminiscent of molasses or licorice in flavor. The primary sugar in birch syrup is fructose, compared to maple, which contains mostly sucrose. The former is touted to be an easier sugar to digest and also contains the lowest glycemic index of all sugars, which makes it the most suitable sugar for use by diabetics. The syrup boasts a high vitamin C content and good amounts of potassium, manganese, thiamin, and calcium.

While maple and black walnut saps run in response to dramatic changes in temperature dynamics (also known as stem pressure), birch sap operates off root pressure, which requires that temperatures stay above freezing day and night. Thus, since collection and boiling equipment is the same, birch could be seen as a form of season extension for sugarmakers.

In 2012 researchers at the Cornell Maple Program station in Lake Placid, New York, tapped around four hundred birch trees and produced about 30 gallons of syrup. Mike Farrell, director of the program, plans to expand production to six hundred to seven hundred trees and develop a significant research and Extension effort on “the biological, technological, processing and economic aspects of birch and walnut syrup production.” Research objectives include determining the best times for tapping, sugar concentrations of trees, consumer preferences, and the impact on lumber quality, along with looking at the economics.

Reprinted with permission from Farming the Woods by Ken Mudge and Steve Gabriel and published by Chelsea Green Publishing, 2014. Buy this book from our store:Farming the Woods.

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